1. Field of the Invention
The present invention relates to an endoscopic insertion instrument, and more particularly relates to the insertion instrument formed to have a small diameter.
2. Description of the Prior Art
An endoscope for medical use generally comprises an operation unit connected to an insertion instrument for inserting into body cavity, etc. and a universal cord to be connected from the operation unit at least to a light source unit. The insertion instrument comprises, from the side of the distal end in order, a hard end portion, an angle portion, and a flexible portion. The hard end portion is provided with at least illuminating means and observing means. In addition to these means, the hard end portion is also provided an channel for inserting treating tools such as forceps therethrough.
The illuminating means includes a light guide and a lens for illumination disposed so as to face the emitting end of the light guide. The lens for illumination is attached within a lens barrel of the illumination lens and the emitting side of the light guide is inserted into the lens barrel of the illumination lens by a predetermined length. The observing means has an objective optical system and at the image forming position of the objective optical system is placed a solid-state imager such as a CCD is arranged or the incidence end of an image guide faces. An optical element including at least one objective lens of the objective optical system is attached within an image lens barrel. The solid-state imager is fixed to the image lens barrel. When using the image guide, the incident side thereof is connected to the image lens barrel. The channel for inserting treating tools is formed of a flexible tube and its fore end is fitted to a hard pipe.
In the hard end portion, through-holes are formed for inserting the above-mentioned illuminating means, observing means, and channel for inserting treating tools. The illuminating lens barrel, the objective lens barrel, and the pipe for inserting treating tools are passed through these through-holes. In such a manner, the illuminating lens barrel, the objective lens barrel, and the pipe for inserting treating tools are fixed to the through-holes formed at the hard end portion. Among various fixing methods, there is firstly a joining method using an adhesive, etc. As to at least the objective lens barrel, a fixing method that set screws are threaded on the side face of the hard tip portion so as to press the set screws against the external peripheral surface of the objective lens barrel is generally adopted.
Of the above-mentioned fixing methods of the illuminating lens barrel, the objective lens barrel, and the pipe for inserting treating tools, the direct fixing by means of the adhesive, etc. causes difficulty in disassembling these members after they are fixed. Therefore, there is a problem that repairs and replacement of these members are extremely troublesome or partial repairs thereon cannot be occasionally performed. Another fixing the objective lens barrel with the set screws enables easily repairs and parts replacement of the observing means. However, the fixing method with set screws has a problem that the external diameter of the hard end portion increases by the dimension required for fixing the set screws. In particular, when the external diameter of the insertion instrument must be extremely reduced in order to insert it into a small-diameter coeliac tract, set screws cannot be used practically for the fixing""s sake.
In view of these problems, the present invention has been made, and it is an object thereof to fix each of members to be attached to an insertion instrument to a hard end portion of the insertion instrument so as to be easily detachable manner without particularly increasing the diameter of the hard end portion.
It is another object of the present invention that in an endoscope having a small-diameter insertion instrument, at least an illuminating lens barrel and an objective lens barrel to be attached to the hard end portion are enabled to be detachably fixed in a precisely positioned state.
In order to achieve the above-mentioned objects, according to the present invention, an insertion instrument for an endoscope which comprises: a hard end portion; an illuminating means fixed to the hard end portion having at least an illuminating lens attached within an illuminating lens barrel and a light guide having an emitting end for facing said illuminating lens; an observing means fixed to the hard end portion having at least an objective optical system disposed within an objective lens barrel; the hard end portion being divided into a holding member and a cover member detachably fitted to the holding member; concave shaped recesses provided between the holding member and the cover member for inserting at least the illuminating lens barrel and the objective lens barrel from outer periphery of the holding member inwardly in the radial direction, wherein the recess have a arc shaped portions to substantially coincide with outer diameters of the illuminating lens barrel and the objective lens barrel; and detachable positioning means for positioning the illuminating lens barrel and the objective lens barrel in the recesses in the axial direction.
Preferably, the holding member further comprises a recess for guiding being formed of a treating tool insertion pipe to be fitted into a treating tool channel, and thereby the concave grooves are formed in the holding member at three positions spaced by an angle of approximately 120xc2x0 so that the illuminating lens barrel, the objective lens barrel, and the treating tool insertion pipe is placed in the concave recess with positioned in the axial direction by the positioning means. There are formed clearances in the abutting portion between the holding member, and the cover member and between the insertion portions and the external peripheral faces of the illuminating lens barrel, the objective lens barrel, and the treating tool pipe. These clearances may be filled with a sealing material so as to maintain airtightness in these inserted portions. In a case where the hard end portion is prefered to be connected to an angle portion consisting of a bendable pipe sequentially and pivotally connecting a predetermined number of angle rings to each other and an outer cover layer formed of a net and an elastic tube for covering the curved pipe, a difference in level is formed at the base end of the holding member for abutting engagement with an angle ring positioned in the end of the curved pipe, whereby the outer cover layer is connected to the cover member and the base end of the cover member is to be abutted to the difference in level in the larger diameter portion of the holding member. Positioning means may be formed of projections respectively formed on the external peripheral faces of, for example, the illuminating lens barrel, the objective lens barrel, and further the treating tool insertion pipe, and concave pits for positioning formed on the respective groove bottom portions of the concave grooves in the holding member so as to be fitted with the respective projections.
The diameters of the illuminating lens barrel, the objective lens barrel, and the treating tool inserting pipe may be substantially the same and the centers of the illuminating lens barrel, the objective lens barrel, and the treating tool insertion pipe may be arranged so that distances from the center of the holding member thereto are substantially the same in the radial direction. Furthermore, the concave grooves formed on the holding member may have cross-sections of substantial a semicircle of the respective outer diameters of the illuminating lens barrel, the objective lens barrel, and the treating tool insertion pipe, and in the cover member, concave grooves having similar semicircular cross-sections may also be formed.
These and other objects, constitutions, and effects of the present invention will become more apparent from the following embodiments of the present invention described with reference to the drawings. Of course the present invention is not understood by limiting to the embodiments.